Investigations into the robbery became inevitably entangled in the political uncertainty of the time. After a meeting with the Policing Board in January 2005, Chief Constable Hugh Orde of the Police Service of Northern Ireland announced at a news conference in Belfast that the Provisional Irish Republican Army (IRA) was responsible for the raid. He added that all the main lines of police inquiry being undertaken at the time were in this direction, not due to any pressure to place blame but because it made ‘operational sense’. He refused to comment on any potential political repercussions this announcement could cause.
“These cases are extremely complicated. The robbery itself was carried out by a competent group of criminals. …This was a particularly brutal crime, people were extremely badly treated and assaulted by the gang.” - Sir Hugh Orde
The Government and other major political figures, with the exception of Sinn Féin, supported this accusation. The IRA denied any involvement in the Northern Bank robbery. Sin Féin MP Martin McGuinness countered that Orde’s allegations were politically biased and more to do with hampering the drive for change to a power-sharing Northern Ireland government, supported by Sin Féin, than anything to do with the robbery. The Prime Minister, Tony Blair, made it clear that a complete end to all criminal and paramilitary activity was necessary for political institutions to be restored. Irish Prime Minister, Bertie Ahern, said that trust and confidence in the peace process had been damaged. It was confirmed that the Independent Monitoring Commission would investigate the matter in due course.
A month later, the IRA was accused of the murder of Robert McCartney, a Catholic father of two small children, on 31 January 2005. These combined accusations put immense pressure on the IRA to sever its criminal links, which led ultimately to the group’s pledge in July 2005 to down arms.
During the investigation, it was revealed that Northern Bank had made no record of the serial numbers of £900,000 worth of the new £100 notes and £250,000 of new £50 notes that were stolen in the raid. In a bid to prevent the gang using all their stolen cash, Northern Bank decided to withdraw its banknotes and re-issue them in a different style and colour, thus eventually making the old currency invalid. On 14 March 2005, in a major security operation, £240 million worth of Northern Bank notes were replaced.